Electrical heating resistance wire and individual resistance rods formed in a spiral pattern are well known, particularly for use in electric stoves. Such heating elements are powered ordinarily by 220 alternating current voltage. Such heating elements are not useful with batteries or other direct current sources, particularly 24 volt or lower energy power sources.
A relatively recent application for electrical heating elements relates to regenerating or cleaning ceramic filter elements clogged with particulates removed from exhaust gases of diesel engines. In this regard, Governments have been increasingly regulating the exhaust emissions of vehicles, particularly diesel-powered vehicles. As a consequence, many organizations have been conducting research into diesel particulate control for trucks, buses, cars, and other vehicles. Cellular ceramic filters have become recognized as being useful in trapping exhaust particulates. As the filters become clogged, however, they must be regenerated or an unacceptable back pressure develops. It is known that one method of periodically regenerating a ceramic filter is to heat the soot-laden front face with an electric heating element. When the proper temperature isreached, particles are incinerated and a flame front travels through the soot pack from front to back. Known heating elements operate typically with alternating current voltages from 50 to 250 volts. U.S. Pat. No. 4,671,058 shows such a device. The heating element comprises electrode plates having a substantially V-shape. The problem with known resistance elements for a ceramic filter regenerating application is that they have not been practical for use with 24 volt vehicle batteries. The present invention overcomes this problem.